How many times have you seen an empty, half-crushed bag lying in the middle of the street and swerved to avoid it? That has to be some kind of species paranoia at work. You never can tell what might be in the bag that might mess up your car, right? How about the sudden horror of realizing you don’t have time to swerve before you hit the bag. Do you breathe a little easier when your car doesn’t explode after you pass over it?
Now imagine instead of just sitting there, maybe blowing a bit in the wind, that the junk in your path was moving at close to 17,400 mph. Imagine sitting on the International Space Station watching a chunk of space trash no more than a foot long zipping toward you, knowing it could kill everyone on board. Ditto for manned space flights.